Question

Assertion :Element formed by the successive emission of 1$\alpha$-particle and 2$\beta$-particles is placed in the same group as the parent element. Reason: $\alpha$-particle is ${[}_2^{4}He{]}^{2+}$ while $\beta$-particle is ${}_{-1}^{0}e$.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

Element formed by the successive emission of 1$\alpha$-particle and 2$\beta$-particles is placed in the same group as the parent element.
$\alpha$-particle is ${[}_2^{4}He{]}^{2+}$ while $\beta$-particle is ${}_{-1}^{0}e$.
When an $\alpha$-particle is emitted, the atomic number decreases by 2 units and when $\beta$-particle is emitted, the atomic number increases by 1.
${}_Z{X}^A{\to }_{Z-2}{Y}^{A-4}{+}_{2}H{e}^4$
${}_Z{X}^A{\to }_{Z+1}{Y}^A{+}_1{\beta }^0$
Thus, both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.